Systems of this type are known, for example from U.S. Pat. No. 7,325,507. This document provides for the steering action, namely, the force exerted on the steering tiller or on the steering arm of the motor through said tiller, to be exerted manually by an operator. The system only exerts an action locking the motor or the rudder and therefore the steering tiller when a change in direction, that is a change in the course, is not desired. This is advantageous since, in presence of very powerful motors or with considerable surfaces of the rudder, the force that has to be exerted on the steering tiller is considerable and has to be maintained all the time, in order to avoid a spontaneous change in the orientation of the rudder blade or of the motor, which, in combination with the hydrodynamic behavior of the watercraft and of the motor, and with reference also to the shape of the propeller, tends to reach the greatest possible pivoting angle of the tiller and of the rudder or of the motor. A situation like this is very dangerous above all when cruising speed is high.
Besides such passive system, document U.S. Pat. No. 6,715,438 describes an active system wherein the steering action performed on the tiller is converted into a control pulse, changing the corresponding steering angle, by an actuator changing the rotation of the motor or of the rudder. This document shows the actuator to be a hydraulic actuator of the type known in hydraulic steering systems used in watercrafts both for moving the blades of the rudder or rudders with inboard motors and for moving the motors when those are of the outboard type.
In both documents, however, the control member, which is composed of an end grip part of the steering tiller, which part is mounted so as to pivot according to an axis substantially parallel to the axis of rotation of the motor or of the rudder blade, operates a valve that opens a circuit supplying the pressurized fluid to one or both the chambers of an actuating cylinder.
In the case of document U.S. Pat. No. 7,325,507, a circuit connects the two chambers of a double-acting cylinder. The opening of the valve, mechanically controlled by the pivoting movement of the end part of the steering tiller with respect to the part associated to the motor, enables the fluid to flow from one to the other chamber of the cylinder and, therefore, makes the tiller free to be pivoted.
In the version where the rotation of the tiller is performed by a non-manual force, the pivoting movement of the end part of the steering tiller always activates, through a control with a valve, the passage of a pressurized fluid from one pressurized tank to the chamber of the cylinder, which, therefore, by being displaced with respect to the rod causes the arm of the motor connected to the cylinder to be displaced.
By bringing back the grip part in the rest position, the valve closes the passage and the movement is locked till the end part of the steering tiller is again operated.
Currently, systems actuating the steering of rudders or outboard motors or the like are also known, which use mechanical actuators that directly transmit, by a transmission for example through cables of the push-pull type, the motion of a steering wheel to the blade or to the motor.
Moreover, systems are known that use combinations of electromechanical, electromagnetic, or electrohydraulic actuators.
The provision of valves activating the conditions locking and unlocking the displacement of the steering tiller or activating oil-hydraulic means actuating the steering require quite complicated arrangements and considerable encumbrances. Moreover, the increasing tendency in known modern steering tillers is to mount on the steering tiller a plurality of controls for different functionalities for controlling the watercraft, such as for example controls for motor tilt, controls for trim of motors, controls for the reversing gear of the motor, for controlling the number of revolutions of the motor and so on. This results in more and more reduced spaces available in the steering tiller and is increasingly difficult to avoid interferences between the several mechanisms housed in the tiller body, resulting in potential dangerous conditions or difficult maintenance conditions.